#include <iostream>

using namespace std;
typedef long long  LL;
const int N = 1e5+10;
int a[N],tmp[N];
LL ans=0;
void reverse_pair(int q[],int l, int r)
{
    if (l >= r) return;

    int mid = r + l >>1;
    
    reverse_pair(q, l, mid), reverse_pair(q, mid + 1, r);
    
    int k = 0,i = l,j = mid + 1;
    while (i <= mid && j <= r)
        if (q[i] <= q[j]) tmp[k ++ ] = q[i ++ ];
        else 
        {
            tmp[k ++ ] = q[j ++ ];
            ans+= mid-i+1;
        }
    while (i <= mid) 
    {
        tmp[k++] = q[i ++ ];
        
    }
    while (j <= r)
    {
        tmp [k++] = q[j ++ ];

    } 
    for( i = l , j = 0; i <= r ; i ++, j ++) q[i] = tmp[j];
}

int main(){
    int n;
    scanf(" %d",&n);
    for(int i =0;i<n;i++) scanf("%d",&a[i]);
    reverse_pair(a,0,n-1);
    cout<<ans;

    return 0;
}